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Biomedical subjects

H Schreier

Publications and source records attributed to H Schreier.

At least 19 recordsLinked to original sources
PubMed2001

Expression of DeltaF508 CFTR in normal mouse lung after site-specific modification of CFTR sequences by SFHR.

The development of gene targeting strategies for specific modification of genomic DNA in human somatic cells has provided a potential gene therapy for the treatment of inherited diseases. One approach, small fragment homologous replacement (SFHR), directly targets and modifies specific genomic sequences with small fragments of exogenous DNA (400-800 bp) that are homologous to genomic sequences except for the desired modification. This approach has been effective for the in vitro modification of exon 10 in the cystic fibrosis transmembrane conductance regulator (CFTR) gene in human airway epithelial cells. As another step in the development of SFHR for gene therapy, studies were carried out to target and modify specific genomic sequences in exon 10 of the mouse CFTR (mCFTR) in vivo. Small DNA fragments (783 bp), homologous to mCFTR except for a 3-bp deletion (DeltaF508) and a silent mutation which introduces a unique restriction site (KpnI), were instilled into the lungs of normal mice using four different DNA vehicles (AVE, LipofectAMINE, DDAB, SuperFect). Successful modification was determined by PCR amplification of DNA or mRNA-derived cDNA followed by KpnI digestion. The results of these studies showed that SFHR can be used as a gene therapy to introduce specific modifications into the cells of clinically affected organs and that the cells will express the new sequence.

Animals↗
PubMed2000

Nuclear gene targeting using negatively charged liposomes.

Oligonucleotides are a very useful tool to control gene activity. Oligos work by complementary base-pairing with target sequences either in the nucleus or in the cytosol (Zelphati, O., Szoka, F.C., Jr., 1996. Liposomes as a carrier for intracellular delivery of antisense oligonucleotides: a real or magic bullet? J. Contr. Rel. 41, 99-119). In a new approach using chimeric oligonucleotides (Yoon, K., Cole Strauss, A., Kmiec, E.B., 1996. Targeted gene correction of episomal DNA in mammalian cells mediated by a chimeric RNA-DNA oligonucleotide. Proc. Natl. Acad. Sci. USA 93, 2071-2076) conversion of single base mutations with help of intranuclear repair mechanisms maybe an advantageous method to cure genetic diseases which are based on single point mutations. These chimeric oligonucleotides are constructed in a way that they form an intramolecular double strand of DNA and modified RNA-bases. We used a fluorescent labelled pure 68-mer DNA-analogue of a chimeric oligonucleotides to follow the intracellular fate of these kind of genetic material. The oligos were complexed with protamine sulfate and coated with three different liposomal formulations. The AVE-3 formulation shows enhanced properties compared to a classical neutral and negatively charged formulation. Nuclear localisation of oligos could only be observed with the AVE-3 formulation. Furthermore only the negatively charged liposome formulations interact with the protamine-complexed oligonucleotides.

Biological Transport↗
PubMed2000

Nuclear transport of oligonucleotides in HepG2-cells mediated by protamine sulfate and negatively charged liposomes.

PURPOSE: The aim of this study was to characterize the intracellular fate and nuclear uptake kinetics of oligonucleotides (ON) that were complexed with protamine sulfate (PS) and negatively charged liposomes at different ratios of ON to PS. METHODS: Double-fluorescence labelling of ON and liposomal lipid was applied to simultaneously monitor the interaction as well as the individual fate of active agent and carrier upon intracellular delivery using confocal laser scanning microscopy (CLSM). A DNA-analogue of a 68-mer intramolecular double-stranded RNA:DNA-hybridoligonucleotide (chimeraplasts) with unmodified phosphate backbone was employed. This construct was condensed with PS and coated with a liposomal formulation (AVE-3 = artificial viral envelope). RESULTS: PS-ON complexes and AVE -3-coated complexes with a defined composition were very effective in nuclear transport of ON for a ON:PS charge ratio of 1:3. Nucleus:cytosol fluorescence ratios peaked at about 10 hrs and started to decrease again at 21 hrs. CONCLUSIONS: AVE associates with PS-condensed ON, and this complex is able to be taken up by cells and to deliver ON to the nucleus. PS-ON complexes are released from the liposomal formulation, mainly as an extranuclear enzymatic degradation of the liposomal phospholipids. The results of the kinetic analysis can be used to optimize transfection protocols with ON in HepG2 cells.

Anions↗
PubMed2000

An innovative topical drug formulation for wound healing and infection treatment: in vitro and in vivo investigations of a povidone-iodine liposome hydrogel.

BACKGROUND: In topical wound treatment, the combination of anti-infectious therapy and a healing-promoting moisturization has not been accomplished yet. OBJECTIVE: Evaluation of a new topical drug consisting of a povidone-iodine (PVP-I) liposome hydrogel allowing for both antiseptic and moist treatment. METHODS: Pharmaceutical formulation of a complex of PVP-I (3%) and phosphatidylcholine in a hydrogel. In vitro, interaction of the complex with relevant micro-organisms was analysed by electron microscopy. Antimicrobial activity was investigated using Staphylococcus aureus in a suspension test. Tissue toxicity was examined by an explantation test in a rodent model. A randomized clinical study on efficacy and tolerability in wound healing was carried out on 35 patients with mesh grafts in parallel groups (PVP-I liposome hydrogel vs. Bactigras) for proof of concept in humans. RESULTS: A direct interaction of the PVP-I liposomes with micro-organisms by attachment to the cell surface was documented. A significantly better microbicidal activity and tissue tolerability of the PVP-I liposome hydrogel compared to conventional PVP-I formulations was shown. The results of the clinical study, especially measurements of neo-epithelization per time and transplant loss, demonstrate significant differences in favour of the PVP-I liposome hydrogel. CONCLUSION: The novel PVP-I liposome hydrogel combines microbicidal and wound healing activities resulting in enhanced epithelization.

Anti-Infective Agents, Local↗
PubMed1998

Malaria circumsporozoite protein inhibits protein synthesis in mammalian cells.

Native Plasmodium circumsporozoite (CS) protein, translocated by sporozoites into the cytosol of host cells, as well as recombinant CS constructs introduced into the cytoplasm by liposome fusion or transient transfection, all lead to inhibition of protein synthesis in mammalian cells. The following findings suggest that this inhibition of translation is caused by a binding of the CS protein to ribosomes. (i) The distribution of native CS protein translocated by sporozoites into the cytoplasm as well as microinjected recombinant CS protein suggests association with ribosomes. (ii) Recombinant CS protein binds to RNase-sensitive sites on rough microsomes. (iii) Synthetic peptides representing the conserved regions I and II-plus of the P.falciparum CS protein displace recombinant CS protein from rough microsomes with dissociation constants in the nanomolar range. (iv) Synthetic peptides representing region I from the P.falciparum CS protein and region II-plus from the P.falciparum, P.berghei or P.vivax CS protein inhibit in vitro translation. We propose that Plasmodium manipulates hepatocyte protein synthesis to meet the requirements of a rapidly developing schizont. Since macrophages appear to be particularly sensitive to the presence of CS protein in the cytosol, inhibition of translation may represent a novel immune evasion mechanism of Plasmodium.

Amino Acid Sequence↗
PubMed1998

Effect of dose and release rate on pulmonary targeting of liposomal triamcinolone acetonide phosphate.

PURPOSE: To demonstrate the importance of dose and drug release rate for pulmonary targeting of inhaled glucocorticoids using an animal model of intrapulmonary drug deposition. METHODS: Liposomes composed of 1,2-distearoyl phosphatidylcholine (DSPC), 1,2-distearoyl phosphatidylglycerol (DSPG) and triamcinolone acetonide phosphate (TAP) or liposomes containing triamcinolone acetonide (TA) were prepared by a mechanical dispersion method followed by extrusion through polycarbonate membranes. Encapsulation efficiency was assessed after size exclusion gel chromatography by reverse phase HPLC. The effect of liposome size (200 nm and 800 nm) on the release kinetics of water-soluble encapsulated material was determined in vitro at 37 degrees C using 6-carboxyfluorescein as a marker and Triton X-100 (0.03%) as a leakage inducer. To investigate the relationship between drug release and pulmonary targeting, 100 micrograms/kg of TAP in 800 nm liposomes was delivered to male rats by intratracheal instillation (IT) and the results compared to data for 100 micrograms/kg TA liposomes (recently shown to exhibit a rapid drug release under sink conditions) and to previous studies reported for an equal dose of TAP in solution and TAP in 200 nm (1). Pulmonary targeting was assessed by simultaneously monitoring glucocorticoid receptor occupancy over time in lung and liver using an ex vivo receptor binding assay as a pharmacodynamic measure of glucocorticoid action. To assess the effect of dose on pulmonary targeting experiments were performed using 2.5, 7.5, 25, 100, and 450 micrograms/kg of TAP in 800 nm liposomes. RESULTS: The in vitro efflux of 6-carboxyfluorescein from (DSPC:DSPG) liposomes after exposure to Triton-X was biexponential. The terminal half-lives of 3.7 h and 9.0 h for the 200 nm and 800 nm liposomes, respectively, demonstrated that larger liposomes promote slower release of encapsulated water-soluble solute while previous results already indicated that encapsulation of lipophilic TA does not result in sustained release. Pulmonary targeting, defined as the difference between cumulative lin and liver receptor occupancies was most pronounced for the 800 nm liposomes (370%xh), followed by the 200 nm preparation (150%xh). No targeting was observed for TAP in solution (30%xh) or the rapid releasing TA liposome preparation. Correspondingly, the mean pulmonary effect time (MET) increased from 2.4-3.0 hr for TA liposomes or TAO in solution to 5.7 h and > 6.2 h for TAP in 200 nm and in 800 nm liposomes, respectively. Escalating doses of TAP encapsulated in 800 nm liposomes revealed a distinct bell shaped relationship between the TAP dose and pulmonary targeting with a maximum occurring at 100 micrograms/kg (370%xh). CONCLUSIONS: The in vivo data presented here confirm that pulmonary residence time and dose affect the extent of lung targeting of glucocorticoids delivered via the lung.

Animals↗
PubMed1998

Simulated lung transfection by nebulization of liposome cDNA complexes using a cascade impactor seeded with 2-CFSME0-cells.

The aim of this study was to devise a simulation aerosol system for quasirealistic gene transfection that could eventually be used to study the characteristics of aerosol delivery, stability, delivery efficiency, and expression efficacy of gene products. It consisted of (1) a PARI aerosol generator and PARI LL jet; (2) an Andersen cascade impactor with a calibrated vacuum pump, fitted with a glass "throat," nebulizer in which stages were seeded with pulmonary cells of interest (e.g., 2-CFSME0-); and (3) a hot room set to 37 degrees C and approximately 70% relative humidity. Cell viability remained at 95% to 99%. A prostaglandin G/H synthase (PGH)- and a human alpha 1-antitrypsin (AAT)-expressing plasmid, respectively, driven by a cytomegalovirus promoter (pCMV4-PGH, pCMV4-AAT) and a heat-insensitive placental alkaline phosphatase (PAP)-expressing plasmid driven by a Rous sarcoma virus promoter (pRSV-PAP) were employed; cationic liposomes consisted of N-[1-(2,3-dioleyloxy)propyl]-N,N,N-trimethylammonium chloride/dioleoylphosphatidylethanolamine (DOTMA/DOPE) or 3 beta-[N-(N',N'-dimethylaminoethane)-carbamoyl]-cholesterol/DOPE (DC-Chol/ DOPE). The fluorescent dye Toto-1 was used to visualize aerosol distribution and to monitor cellular uptake. Alternatively, pCMV4-PGH deposited onto impactor stages covered with nitrocellulose membranes was hybridized with random primer-32P-radiolabeled pCMV4-PGH and autoradiographed. The mass median aerodynamic diameter (MMAD) of the plasmid, liposomes, and liposome-plasmid complexes and their effect on the mass output were monitored. A majority of gene product was delivered to stages 1 through 5, corresponding to an area ranging from the pharynx to the terminal bronchi, excluding the alveolar space. A corresponding, although very low, transfection of cells with pRSV-PAP was found, with the majority of transfected cells on stages 4 and 5. The MMAD was significantly affected by the presence of the DNA constructs alone or by DNA constructs complexed with cationic liposomes; the control phosphate buffered saline (PBS) MMAD of 2.3 microns increased to 3.5 microns for DC-Chol liposomes and 4.5 microns for the DC-Chol/PGH complex; DOTMA-based liposomes and liposome DNA complexes precipitated during aerosolization. Mass output was reduced for cationic liposomes from 0.61 g/min (PBS control) to 0.35 g/min. Large plasmid (pRSV-PAP, 10.1 kb) was more rapidly degraded by aerosolization than smaller plasmid (pCMV4-AAT, 6.2 kb) although complexation with cationic liposomes provided some protection in both cases.

Aerosols↗
PubMed1998

[Molecular effects of a microbicidal substance on relevant microorganisms: electron microscopic and biochemical studies on povidone-iodine].

The microbicidal activity of the broad spectrum antimicrobial agent povidone-iodine is due to the strong oxidizing effects of free iodine on functional groups of amino acids, nucleotides and double bonds of unsaturated fatty acids. While the chemical mechanism of action of PVP-iodine is well understood, the actual sequence of events on the cellular and molecular level that causes rapid cell death has not been fully understood. The aim of this study was to elucidate effects of povidone-iodine on cell ultrastructure by electron microscopy and to monitor changes in enzyme activity and nucleotide efflux. Staphylococcus aureus, E. coli and C. albicans, medically relevant gram-positive, gram-negative and yeast micro-organisms, served as models. In the presence of povidone-iodine, rapid partitioning of the cytoplasm and pronounced coagulation of nuclear material was noted. Especially C. albicans exhibited a rapid, dose-dependent "loosening" of the cell wall; cells remained intact without lysis, rupture or wall breakage. Changes in beta-galactosidase and nucleotide concentrations were measured in E. coli. A rapid and dose-dependent loss of cellular beta-galactosidase activity was found, with no increase in the supernatant; loss of cellular nucleotides corresponded with an increase in the supernatant. Electron microscopy and biochemical observations support the conclusion that povidone-iodine interacts with cell walls of micro-organisms causing pore formation or generating solid-liquid interfaces at the lipid membrane level which lead to loss of cytosol material, in addition to enzyme denaturation. The chemical mechanism of action explains the fact that povidone-iodine does never generate resistance in micro-organisms.

Anti-Infective Agents, Local↗
PubMed1997

Physicochemical properties and in vitro toxicity of cationic liposome cDNA complexes.

The purpose of this study was to elucidate the interaction of cationic liposomes and plasmid cDNA by examining their ultrastructure, zeta potential, stability in aqueous media and protection from DNaseI digestion; their potential for hemolysis and platelet aggregation was evaluated as it may serve as an in vitro toxicity screen. Liposomes consisting of N-[1-(2,3-dioleyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA) or 3 beta-[N-(N',N'-dimethylaminoethane)-carbamoyl]-cholesterol (DC-Chol) and dioleylphosphatidylethanolamine (DOPE) were complexed with plasmid constructs of ovine prostaglandin G/H synthase (pCMV4-PGH) or human alpha 1-antitrypsin (pCMV4-AAT) at lipid:plasmid (L/P) ratios of 3:1-8:1 (w/w). The electron micrographs showed bead-like attachment of liposomes to cDNA and coating of plasmid strands. The zeta potential showed isoelectric points at L/P ratios of 3.5-4 (DOTMA/DOPE) and 5.5-6.5, corresponding to a pKa of 6.45 (DC-Chol/DOPE). Liposome cDNA complexes were stable in water, saline and 5% dextrose for 48 h, but precipitated instantaneously in PBS. An increase in the L/P ratio corresponded with increased protection from DNaseI digestion. DOTMA/DOPE liposomes alone were highly hemolytic and DC-Chol/DOPE liposomes moderately hemolytic; hemolysis was abolished by cDNA complexation, with the exception of very high (> or = 7:1) L/P ratios. Both liposomes alone and cDNA complexes caused transient serum turbidity, while none caused platelet aggregation. It was concluded that current cationic lipid cDNA formulations are metastable and appear to have very little if any toxicity with respect to hemolytic potential and untoward interaction with other blood components.

DNA, Complementary↗
PubMed1997

Povidone-iodine liposomes--an overview.

In recent years, liposomes have been increasingly explored as novel drug delivery systems, and several liposome-based drug products have been approved in Europe, the USA and Japan. Depending on size, composition and surface characteristics, liposomes interact specifically with biological structures. Liposomal drug products provide a topical activity at the desired locus of action and are deemed more effective and less toxic than conventional drug formulations. The combination of povidone-iodine (PVP-I) and liposomes unites the exceptional microbicidal activity of the antiseptic substance with the excellent tolerability and lack of immunogenicity of liposomes; in addition, liposomes provide a moist molecular film for the wound environment. The multilamellar vesicles act as microreservoirs hence prolonging the release of the active ingredient. Although no commercial product for repeated application on the eye is currently available, PVP-I has been used in ophthalmology not only for pre- and postoperative antisepsis, but also for the treatment of bacterial and viral conjunctivitis and for prophylaxis against ophthalmia neonatorum. For these indications, liposomal formulations with 2.5 and 5.0% PVP-I were developed. These eye drops are isotonic with tear fluid at pH 6. First in vitro tests demonstrated an excellent antimicrobial efficacy, and a placebo-controlled clinical study on volunteers showed a very good local tolerability. A study on rabbits demonstrated positive results of the PVP-I liposome eye drops compared to placebo and the broadspectrum antibiotic Polyspectran in a standardized model of Staphylococcus aureus deep eye infection. The other aim is a well-tolerated liposomal PVP-I hydrogel for improved antiseptic wound treatment with moisturizer. It has been reported that liposomes are enriched at the wound bottom for direct action against infection and support of wound healing. An animal study on the efficacy and tolerability of different formulations of a hydrogel with PVP-I liposomes in deep dermal burn wounds has indicated an outstanding quality of wound healing with smooth granulation tissue, less inflammation, less wound contraction and no hyperkeratotic reactivity, especially with the 3% PVP-I liposome formulation.

Administration, Cutaneous↗
PubMed1997

Molecular effects of povidone-iodine on relevant microorganisms: an electron-microscopic and biochemical study.

The aim of this study was to elucidate the effects of povidone-iodine (PVP-I) on cell ultrastructure by electron microscopy and to monitor changes in enzyme activity and nucleotide efflux. Staphylococcus aureus, Escherichia coli and Candida albicans, medically relevant gram-positive, gram-negative and yeast microorganisms, served as models. In the presence of PVP-I, rapid partitioning of the cytoplasm and pronounced coagulation of nuclear material was noted. E. coli and S. aureus showed no major structural wall damage. C. albicans exhibited a rapid, dose-dependent 'loosening' of the cell wall; cells remained intact without lysis, rupture or wall breakage. Changes in beta-galactosidase and nucleotide concentrations were measured in E. coli. A rapid and dose-dependent loss of cellular beta-galactosidase activity was found, with no increase in the supernatant; loss of cellular nucleotides corresponded with an increase in the supernatant. Electron-microscopic and biochemical observations support the conclusion that PVP-I interacts with cell walls of microorganisms causing pore formation or generating solid-liquid interfaces at the lipid membrane level which lead to loss of cytosol material, in addition to enzyme denaturation.

Anti-Infective Agents, Local↗
PubMed1996

Water dynamics and population pressure in the Nepalese Himalayas.

The authors investigate the impact of water shortages, especially water for irrigation, on development in Nepal. "The problems associated with hydropower development will be illustrated by using the Kulekhani watershed project as a case study." The possible future effects on food supplies and health are discussed.

Asia↗
PubMed1996

Pulmonary targeting of liposomal triamcinolone acetonide phosphate.

PURPOSE: To explore the use of triamcinolone acetonide phosphate liposomes as a pulmonary targeted drug delivery system. METHODS: Triamcinolone acetonide phosphate liposomes composed of 1,2-distearoyl phosphatidylcholine and 1,2-distearoyl phosphatidyl glycerol and triamcinolone acetonide 21-phosphate dipotassium salt were prepared by dispersion and extruded through polycarbonate membranes. Encapsulation efficiency and in vitro stability at 37 degrees C were assessed after size exclusion chromatography. TAP liposomes (TAP-lip) or TAP in solution (TAP-sol) were delivered to rats either by intratracheal instillation (IT) or intravenous (IV) administration. Pulmonary targeting was assessed by simultaneous monitoring of glucocorticoid receptor occupancy over time in lung (local organ) and liver (systemic organ) using an ex vivo receptor binding assay as a pharmacodynamic measure of glucocorticoid action. RESULTS: In vitro studies in different fluids over 24 hours, showed that more than 75% of the TAP remained encapsulated in liposomes. Cumulative pulmonary effects after IT administration of TAP-lip were 1.6 times higher than liver receptor occupancy. In contrast, there was no difference in the pulmonary and hepatic receptor occupancy time profiles when TAP was administered intratracheally as a solution. No preferential lung targeting was observed when TAP-lip was administered IV. As indicated by the mean effect times, lung receptor occupancy was sustained only when TAP-lip was administered IT. CONCLUSIONS: Intratracheal administration of TAP-lip provided sustained receptor occupancy, and increased pulmonary targeting which was superior to IT administration of TAP-sol or IV administration of TAP-lip. The use of liposomes may represent a valuable approach to optimize sustained delivery of glucocorticoids to the lungs via topical administration.

Animals↗
PubMed1995

Assessment of glucocorticoid lung targeting by ex-vivo receptor binding studies in rats.

Triamcinolone acetonide (TA, 22 micrograms) was given to rats by intravenous (i.v.) injection or intratracheal (IT) instillation. Free glucocorticoid receptors were monitored over time in liver and lung using an ex-vivo receptor binding technique. After i.v. administration of a TA solution, the reduction of free receptors over time was very similar in lung and liver (AUCLung = 280 +/- 47% h; AUCLiver = 320 +/- 76% h). Intratracheal instillation of the same solution produced time profiles which mirrored those of i.v. injection (AUCLung = 260 +/- 41% h; AUCLiver = 330 +/- 50% h). The lack of lung targeting was also reflected in the failure to show any significant difference in the pulmonary targeting factor T (AUCLung/AUCLiver) between i.v. (T = 0.84 +/- 0.18) and IT (T = 0.78 +/- 0.03) administration. In contrast, a certain degree of lung specificity was observed after IT instillation of a glucocorticoid suspension (22 micrograms; AUCLung = 160 +/- 135% h; AUCLiver = 65 +/- 91% h, T = 2.3 +/- 0.5) as indicated by significant differences in T between i.v. injection and IT instillation (p = 0.038). The method presented provides a means of simultaneously assessing pulmonary and systemic effects after different forms and routes of administration and might be of value in further studying multiple aspects of inhalation glucocorticoid therapy.

Animals↗
PubMed1994

Targeting of liposomes to cells expressing CD4 using glycosylphosphatidylinositol-anchored gp120. Influence of liposome composition on intracellular trafficking.

To test the concept that glycosylphosphatidylinositol (GPI)-anchored proteins might be useful as targeting molecules for liposomes, we engineered a GPI-anchored form of gp120 from human immunodeficiency virus type 1 (termed gp120DAF) using the GPI signal of decay-accelerating factor (DAF). We show that (i) purified gp120DAF spontaneously inserts into liposome membranes via the GPI anchor; (ii) liposomes bearing gp120DAF bind specifically to cells expressing CD4, the cellular receptor for gp120; and (iii) the receptor-bound liposomes are internalized and recycle in Chinese hamster ovary cells. To test whether the lipid composition of the liposome affects any of these processes, we compared small unilamellar liposomes containing only phosphatidylcholine and cholesterol in a 7:1 molar ratio with artificial viral envelopes that mimic the lipid composition of human immunodeficiency virus type 1. We show that when tagged with gp120DAF, both liposome preparations bind specifically to cells expressing CD4, and both are endocytosed. However, artificial viral envelope liposomes are transported to late endosomes or lysosomes in the cell interior, whereas phosphatidylcholine:cholesterol liposomes are confined to a population of vesicles that remain close to the plasma membrane. Since the binding and internalization of both liposome preparations are mediated by the same receptor, we conclude that the lipid composition of the liposome profoundly influences the subsequent intracellular trafficking of the liposome-receptor complex.

Animals↗
PubMed1994

The new frontier: gene and oligonucleotide therapy.

Gene and oligonucleotide therapy are emerging as clinically viable therapeutic regimens for genetic, neoplastic, and infectious diseases. Approaches include insertion of human genes in viral vectors including recombinant retrovirus, adenovirus, adeno-associated virus, and herpes simplex virus-1, or recombinant bacterial plasmids. Viral vectors transfect cells directly; plasmid DNA is delivered with the help of cationic liposomes (lipofection), polylysine conjugates, gramicidin S, artificial viral envelopes or other such intracellular carriers. Major areas of interest include replacement of the cystic fibrosis transmembrane regulator gene and the alpha 1-antitrypsin gene; arrest of human immunodeficiency virus infection; and reversal of tumorigenicity and cancer immunization, among others. Oligonucleotide therapy is principally focusing on the same areas, although the approach is to halt DNA transcription or messenger RNA translation with code-blocking triple-helix-forming or "antisense" oligomers. Contributions from the pharmaceutical sciences are expected in pharmaceutical chemistry, drug delivery systems design, analytical chemistry, and biopharmaceutics.

Animals↗
PubMed1994

Pharmacokinetics of detirelix following intratracheal instillation and aerosol inhalation in the unanesthetized awake sheep.

The unanesthetized awake sheep was employed as large animal model for the determination of bioavailability and pharmacokinetics following the pulmonary instillation of the decapeptide detirelix. After intratracheal administration of a 80 micrograms/kg dose, the average t1/2 of elimination was 9.8 +/- 1.3 hours (n = 5) which was similar to the elimination kinetics of a 30 micrograms/kg i.v. dose (7.2 +/- 2.9 hours). Mean residence time (MRT) was prolonged to 10.3 +/- 2.0 hours vs. 2.7 +/- 0.8 hours i.v., and mean absorption time (MAT) was calculated to be 7.5 +/- 1.8 hours. Maximum plasma levels (cmax) of 9.2 ng/ml were reached after 2 hours. The average bioavailability was 9.8 +/- 3.9% of the dose. The pharmacokinetic profile was found to be similar after aerosol administration. It was concluded that detirelix was absorbed systemically when administered by pulmonary instillation or aerosolization and that the unanesthetized awake sheep is a suitable model to study resulting drug profiles.

Administration, Inhalation↗